By a vote of 53 to 38, the Senate failed to break a filibuster of Robert L. Wilkins, a federal judge who was nominated to fill one of three vacancies on the United States Court of Appeals for the District of Columbia Circuit….The impasse over Mr. Wilkins followed Republican blockades of two other candidates for the court since Oct. 31. Unlike previous fights over judicial nominees, the dispute is not as much about the judges’ individual political leanings….Rather, Republicans are seeking to prevent Mr. Obama from filling any of the three existing vacancies on the 11-seat court, fearing that he will alter its conservative tilt.

….Republicans are on the verge of exhausting the last bit of tolerance Democrats have shown for such regular use of the filibuster on nominations. Senator Patrick J. Leahy of Vermont, the Senate’s longest-serving current member, who has fought to safeguard the institution’s traditions, said Monday that momentum was building toward a rules change — a move so controversial that it is referred to as the nuclear option.